THE LIPID-LADEN MACROPHAGE AS A MARKER OF ASPIRATION IN NEONATES WITH CHRONIC LUNG DISEASE

Abstract

The diagnosis of aspiration secondary to gastroesophageal reflux is difficult unless it is massive. In order to determine whether the presence of lipid-laden macrophages in tracheal aspirates is useful diagnostically we prospectively evaluated samples stained with Oil-Red-O in ventilator-dependent neonates fed orogastrically. By grading the amount of intracellular Oil-Red-O per 100 macrophages we computed a semiquantitative index. NPO infants served as controls. Measurement of lactose in the aspirates was used as the index of aspiration and was considered positive when lactose value was >mean+2SD of controls. Forty three aspirates were obtained from 25 neonates. Eleven infants had at least one value of lactose suggestive of aspiration. The mean raacrophage index for aspirators of 194±14 was greater than the index of nonaspirators (122±5, p<0.001). The testing characteristics of lipid indexes were: We conclude that the sole presence of lipid-laden macrophages in lower respiratory secretions is a nonspecific marker of lung disease. However, a computed lipid-laden macrophage index ≥175 is a rapid and specific test that may be helpful in diagnosing aspiration in chronic lung disease.